Origin of irregardless

Can be confusedirregardlessregardless (see usage note at the current entry)

Usage note

Irregardless is considered nonstandard because of the two negative elements ir- and -less. It was probably formed on the analogy of such words as irrespective, irrelevant, and irreparable. Those who use it, including on occasion educated speakers, may do so from a desire to add emphasis. Irregardless first appeared in the early 20th century and was perhaps popularized by its use in a comic radio program of the 1930s.

an erroneous word that, etymologically, means the opposite of what it is used to express. Attested in non-standard writing from at least 1870s (e.g. "Portsmouth Times," Portsmouth, Ohio, U.S.A., April 11, 1874: "We supported the six successful candidates for Council in the face of a strong opposition. We were led to do so because we believed every man of them would do his whole duty, irregardless of party, and the columns of this paper for one year has [sic] told what is needed."); probably a blend of irrespective and regardless. Perhaps inspired by the colloquial use of the double negative as an emphatic.